Electrolytic cell for sharpening the edge of a razor blade



Sept. 30, 1969 a. w. LOVEKIN 3,470,031

' ELECTRQLYTIC CELL FOR SHARPENING THE EDGE OF A RAZOR BLADE Filed March21, 1966 lrwau'rok BARRY w. LOVEKIH BY A T roRNEYS United States PatentOffice 3,470,081 Patented Sept. 30, 1969 3 470,081 ELECTROLYTIC CELL FORSHARPENING THE EDGE OF A RAZOR BLADE Barry W. Lovekin, High Wycombe,England, assignor to Wilkinson Sword Limited, London, England, a Britishcompany Filed Mar. 21, 1966, Ser. No. 536,054 Claims priority,application Great Britain, Mar. 30, 1965, 13,324/ 65 Int. Cl. C23b 5/58U.S. Cl. 204-206 6 Claims ABSTRACT OF THE DISCLOSURE An electrolyticcell for the electroforming or electrofinishing of the cutting edges ofrazor blades is so constructed that there is no physical contact betweenthe electrodes of the cell and the razor blades during the process. Thisis achieved by providing a first chamber for containing electrolyte withwhich the anode is in contact and a second chamber for containingelectrolyte, isolated from the electrolyte in the first chamber, withthe cathode in contact with the electrolyte in the second chamber. Arazor blade is supported with the edge which is to be electroformed orelectrofinished in the electrolyte in the second chamber whilst aportion of the blade behind the edge is in contact with the electrolytein the first chamber. In this way current flows from the anode throughthe electrolyte in the first chamber to the portion of the blade behindthe cutting edge through the blade to the edge which is to beelectroformed or electrofinished and thence through the electrolyte inthe second chamber to the cathode.

This invention relates to electrolytic cells for the production ofcutting edges and, more particularly, to cells for the production of thecutting edges of razor blades.

The cells may be used for the finishing, only, of cutting edges afterinitial formation by other methods, such as abrasive methods, and suchprocessing will be referred to hereafter as electro-finishing. On theother hand, the cells may be used for production of a cutting edge,without prior mechanical shaping, in which case such processing will bereferred to hereafter as electroforming.

According to the present invention there is provided an electrolyticcell for electroforming or electrofinishing the cutting edge of a razorblade wherein there is no physical contact between the blade and theanode of the cell.

The invention also provides an electrolytic cell for electroforming orelectrofinishing the cutting edge of a razor blade comprising means forguiding razor blade strip through the cell and at least one anode solocated that there is no physical contact with the blade strip when itis passing through said guiding means.

There is further provided by the invention an electrolytic cell forelectroforming or electrofinishing the cutting edge of a razor bladecomprising a first chamber adapted to contain electrolyte the anodebeing in contact with the electrolyte, a second chamber adapted tocontain electrolyte, the cathode being in contact with the electrolytein said second chamber, and means for sup porting the razor blade withone edge in contact with the electrolyte in said second chamber and anintermediate portion of the blade in contact with the electrolyte insaid first chamber.

One construction of cell in accordance with the invention will now bedescribed with reference to the accompanying drawing which is aperspective sectional view through the cell.

This construction of cell and its method of operation has been fullydescribed and illustrated in co-pending patent application Ser. No.522,668 assigned to the same assignee as is the present application. Theaforesaid application is directed to those features of the structure ofthe cell which facilitate electroforming or electrofinishing of adesired shape of cutting edge whereas the present application isprimarily directed to those features of the structure of the cell whicheliminate the necessity for physical contact between the anode and theblade.

Referring now to the drawing, it will be seen that the construction isas described and illustrated in the aforesaid application. Thus, thecell comprises a metal housing 10 which constitutes the cathode. Withinthe cathode housing 10 two screening masks 12, 12 of ceramic materialare mounted and the adjacent faces of these are separated by asufiicient distance to allow the passage of metal strip 13, in the formof razor blade blanks joined end-to end and with a central slot alreadypunched. The strip 13 makes a sliding fit with the faces of masks 12,12. The masks 12, 12 each have a central aperture in which an elongatedanode 14 is mounted to form an electrolyte containing anode chamber 12a,12a between the blade strip 13 and the respective anode 14, 14. Themasks 12, 12 are also shaped to provide cathode chambers 12b, 12b.

For other details of the cell construction and the methods ofelectroforming or electrofinishing reference should be made to thespecification and drawings filed with the aforesaid application.

The current path is from each anode 14 through the electrolyte in itsrespective anode chamber 12a to the central portion of the blade strip13, through the blade strip to the exposed surface at each edge andthence through the electrolyte in the respective cathode chamber 12b tothe cathode 10.

The construction described has the great advantage that it is notnecessary for there to be physical contact between the anode and theblade strip. Such physical contact suffers from the disadvantage thatthere is a liability for arcing to occur between the anode (or contactstrip at anode potential) and the moving blade strip and that inevitablywear of the anode (or contact strip) occurs.

Any tendency for metal to be plated onto the central blade strip can beprevented or reduced by selecting an anode material which does notdissolve in the required manner for plating out, examples beingrhodium-plated anodes such as rhodium-plated copper, lead anodes andgraphite anodes. Alternatively, the anodes may consist of a coating of aprecious metal on a base metal of anodically polarisable material.Whilst for this purpose we prefer to use a platinum coated or cladtitanium base it is also possible to employ plating of other preciousmetals, for example rhodium, gold or irridium. These metals are goodconductors and have the advantage that they do not dissolve in theelectrolyte. It is desirable to use a base of anodically polarisablematerial so that if there are any pin holes in the plating the base willnot be dissolved. Tungsten is another material which can be used for thebase but it is more diflicult to machine than titanium and moreexpensive.

It will be appreciated that only one anode member is necessary but thatgreater efficiency can be obtained by the use of two. Moreover, theanodes need not be planar but can have any appropriate shape for maximumcurrent efficiency. Thus, as an alternative to having anodes in the formof strips the anodes may be in the form of rods, the circularcross-section having the advantage of maximum surface area for a givencross-section.

I claim:

1. In an electrolytic cell for at least finishing the cutting edge of arazor blade,

an elongated cathode,

at least one elongated anode, and

guide means for supporting a razor blade having at least one unfinishedcuting edge in predetermined position relative to said cathode and saidanode, said guide means and said cathode defining a first elongatedspace for containing electrolyte in contact with said cathode, saidunfinished cutting edge projecting into said electrolyte with thecathode lying opposite said unfinished cutting edge throughout itslength, said guide means and said anode defining a second elongatedspace for containing further electrolyte in isolation from theelectrolyte in said first space and in contact with said anode and witha portion of the blade lying behind said unfinished edge, said anodelying opposite said portion of the blade throughout its length, wherebyin operation current flows from the anode through said furtherelectrolyte to said portion of the blade throughout the length of saidportion, thence to said unfinished cutting edge and from the entirelength of said unfinished cutting edge through the electrolyte in saidfirst space to said cathode.

2. An electrolytic cell according to claim 1, wherein said cathodeconstitutes the cell housing.

3. An electrolytic cell according to claim 1, comprising a secondelongated anode, said guide means and said second anode defining a thirdspace for containing still further electrolyte in contact with saidsecond anode and 4 with said portion of the blade lying behind saidunfinished edge.

4. An electrolytic cell according to claim 3, wherein said razor bladehas a second unfinished edge and wherein said guide means and saidcathode define a fourth space for containing additional electrolyte incontact with said cathode, said second unfinished edge projecting intosaid additional electrolyte.

5. An electrolytic cell according to claim 1, wherein that portion ofthe surface of said anode which is in contact with said furtherelectrolyte in said second space is substantially planar.

6. An electrolytic cell according to claim 3, wherein that portion ofthe surface of said second anode which is in contact with said stillfurther electrolyte in said third space is substantially planar.

References Cited UNITED STATES PATENTS 9/1956 Pullen 204-268 9/1962 Ruff20447 US. Cl. X.R. 20428

